Just yesterday, I discovered that recent snapshots of alsa-driver sources contain patches needed for full support of my sound card in Lenovo Ideapad Y530 laptop. Downloaded, compiled and the sound started to work perfectly again - surround, subwoofer volume level - all that was gone where model=lenovo-sky stoped working along with kernels > 2.6.35.

Today, I installed the new slh kernel and compilation fails with the following error:

ALSA is part of the mainline kernel and at version 1.0.23. If there are issues with it, they need to be fixed once and for all, properly in the kernel. In my personal experiences ALSA upstream monitors bugzilla.kernel.org very closely and is actively responding to problems.

The build issue you're referring to does not happen with in-kernel ALSA - actually it has been fixed in 2007 for kernel 2.6.22, so your local version must even predate that. The problem is not in the kernel, or aptosid's patches, but your ancient out-of-tree kernel module code.

Hmm...
I'm downloading this daily snapshot http://ftp.kernel.org/pub/linux/kernel/ ... ot.tar.bz2
You're telling me that it is out of date? If that error isn't connected to the kernel/aptosid patches then why the same snapshot compiles correctly on the previous aptosid kernel version?

Its compat layer seems to need quite some work and appears to come from the distant past, it will (have to) be fixed quite soon. But if your card stopped working with kernel 2.6.36, why isn't it fixed by 2.6.37 or 2.6.38, if you claim that current upstream development snapshot are working? If there is a bug, it needs to be fixed mainline.

As for my sound problems, on kernels 2.6.35+ the sound works, but only stereo, with poor volume level and of course na subwoofer support.

So there should be a bug filled against the mainline kernel or the upstream alsa? I'm not really familiar with the connections between alsa and kernel, so any help with clearing this would be very appreciated.

Patches get merged to the mainline kernel all the time, be it for daily linux-next snapshot, the 2.6.39 merge window or -stable. If a particular change stays out of mainline for more than 1 kernel cycle, there should be a reason. This also makes it appear to be unlikely that your card fails to work with mainline 2.6.36, 2.6.37 and 2.6.38 - but worked with alsa snapshots released in close temporal proximity to the kernel 2.6.36 release, but are still broken mainline in 2.6.38. About the reasons I can only speculate, be it that a patch simply got forgotten (unlikely), timing issues during module probe (race condition), different configurations/ module parameters kicking in (avoidable by local configuration, like module parameter) or some procedural issue, however it needs to get fixed - mainline.

Correct (I didn't look at the actual patches before), so it's likely that they entered linux-next yesterday and may still make it for 2.6.39; given that all of them are marked for -stable, chances are that they may make it for 2.6.38.1 as well. If you're sufficiently confident that those patches fix your issue, we might even pull those for one of our next kernel updates, before they hit 2.6.39 or -stable.

It's only the inglorious 0019-BKL-That-s-all-folks.patch, which prevents the succsessfuly building of this source.
But it does not care anyone in the aptosid theam.
This patch is also the reason for not building nvidia-source.